There are many reasons why the goalkeeper lost goals.
Through analysis and research, I achieved the conclusion that there are three causes.   

The goalkeeper needs to prepare the following before 
the opponent's  shooting.

1. position
2. set position
3. balance

-Position :       The goalkeeper positions the center of the goal 
                        and the ball in a straight line by adjusting the 
                        distance between them, depending on the 
                        shooting  distance and shooting area.
                        It is likes them A - a,  B - b.

-set position :  The goalkeeper have to be set position in height 
                        to the shooting distance.
                        It is likes A - a( a little bit of high),  
                        B - b (normal set position)

Set position about shooting distance

-Balance      :  The goalkeeper have not to shake the center of 
                       his body at the moment of shooting.